[Experimental studies on healing process of plication technique at postdiscal connective tissue of TMJ in Macaca fuscata].

Abstract

The purpose of this study is to evaluate the healing process following application of the plication technique at the postdiscal connective tissue of the temporomandibular joint (TMJ). Female monkeys (Macaca fuscata) approximately eight years old were subjected to bilateral TMJ operations. The plication technique was performed in the left joint of each animal. In the right TMJ, the only operation performed was the exposure of the upper joint cavity. Results. 1) No synovial cells occurred on any upper surfaces of postdiscal connective tissue in left, first-week, postsurgical specimens. No synovial cells were observed in the area from the lateral to the middle upper surface of postdiscal connective tissues in specimens taken from the control side. Synovial cells gradually regenerated from the outside and, by the fourth postsurgical week, all of them had recovered in specimens from both sides. 2) During the early period, fibrin precipitation, round cell infiltration, fibroblast proliferation, and vascularization occurred in the plicated region. But these symptoms gradually decreased; and, by the twenty-fourth postsurgical week, collagen fibers surrounded the sutures. In the upper cavity, sutures were covered by newly proliferated connective tissue four weeks after surgery. The giant cells that proliferated around sutures in the fourth week increased gradually. 3) From the first postsurgical week, connective tissue proliferated in the lateral and middle parts of the superior postdiscal connective tissue in the right joint. Similar proliferation occurred in the left joint in the inner side of plicated region. Round cell infiltration took place in these connective tissue in the early period but gradually decreased. As this occurred, numbers of fat cells increased. No significant difference was noticed between proliferation in the right and left joints. No adhesion to the synovium in the glenoid fossa was observed. 4) In the first postsurgical week, connective tissue proliferated bilaterally from the posterior edges of both the glenoid fossa and the postdiscal tissue. In the second and fourth postsurgical weeks, connective tissue proliferation formed a fold narrowing the upper joint cavity. 5) Synovial cells were absent from the lateral to the middle region of both glenoid fossa from the first postsurgical week. Regeneration took place from the outside, and all synovial cells had recovered by the fourth postsurgical week. Disappearance of synovial cells was more extensive in the left than in the right glenoid fossa. 6) Round cell infiltration, vascularization, collagen fiber hyalinization, and hyperplasia of the fibrous covering occurred in the lateral part of the fibrous covering of the glenoid fossa but gradually decreased.(ABSTRACT TRUNCATED AT 400 WORDS)